Transmission



July 6, 1943; H. s'. EBERHARD 'I'RANSMZCSSION Filed Nov. 26. 1940 6 Sheets-Shae; 1

INVENTOR I Harman J. [bar/74rd ATTORNEY H. .5. EBERHARD 2,323,384

IRANSMISYSION Filefl .Nov. 7 26, 1940 Sheets-Sheet 2 Q "3 INVENTOR Harmon 5 fiber/20rd BY Mk/ 'yw ATTORNEY July 6, 1943. H. s; EBERHARD TRANSMISSION.

Filed Nov. 26, 1940 6 Sheets-Sheet 3 INVENTOR v Harmon 5. Eberhard M fiz' az Y Y ATTORNEY July 6, 1943.

H. s. EBERHARD TRANSMISS ION Filed Nov. 26. "1940 6 Sheets-Sheet 4 ATTORNEY I July 6, 1943. H. s. EBERHARD TRANSMISSION Filed Nov. 26, 1940 e SheetS-Sh eet s I .El.

INVENTOR Harmon I. Eberhard BY ATTORNEY reamed July 6, 1943 I 'RANSMIS SION Harmon S. Eberhard, Peoria, 111., asslgnor to Caterpillar Tractor 00., San Leandro, Calii'., a Corporation of California Application November 26, 1940, Serial No. 367, 237.

2 Claims.

My invention relates to transmissions, and more particularly to speed change transmissions adapted for .vehicles such as tractors.

With respect to vehicles which are called upon to be driven alternately forwardly and backwardly, such as track-type tractors when performing bulldoz'ing work, it is desirable that reversal of the drive'of the tractor after it has been driven forwardly or. backwardly be accomplished with ease and rapidity to facilitate the work of the operator, and also save time thereby making for economy. In this connection, bulldozing work comprises employing a bulldozer blade at the front end of the tractor which is utilized to push earth toa desired location when the tractor-is driven forwardly. when such position is reached, the operator has to reverse the tractor'without a load to line it up for subsequent pushing of more earth to the desired'location. This necessitates constant forward and reverse driving of the tractor.

My invention has "as its'objects, among others, the provision of an improved speed change transmission which is of such character as to-enable with ease and rapidity, reversal of the drive of backwardly; which provides a common reversible drive for any one of a plurality of different speed drives thus obviating the necessity of having to change such different speed drives when the-dia a vehicle after it has been driven forwardly or rection of travel of the vehicle is to be reversed;

which has reversible gearing so located with respect to selective speed change gearing of the' by line 2-2 in Fig. 4.

Fig. 3 is a developed view of the transmission shafts and gearing showing the relative relationship therebetween.

Fig. 4 is a vertical transverse sectional view taken in a plane indicated by line 4-4 in Figs. 1 and 2.

Fig. 5 isa vertical longitudinal sectional elevation of the transmission control mechanism, taken in planes indicated by line 5-5 in Fig. 4.

Fig. 6 is a horizontal section taken in a plane indicated by line 6-4 in Fig. 4.

Fig. 7 is a fragmentary transverse vertical sectional view taken in planes indicated by line 1-1 in Fig. 5.

Flgi 8 is a section taken in a plane indicated by line 8-8 in Fig. '7.

Fig. 9 1s a section taken in a plane indicated by line 8-4 in Fig. '7.

Fig. 10 is a section taken in a plane indicated by line i0lli in Fig. 5.

With reference to Fig. 1, the transmission of my invention is shown in a track-type tractor wherein it has particular applicability because of the nature of the work which such tractor is often called upon to perform. However, such transmission may be employed in any other environment requiring frequent reversal of the drive transmitted thereby. The track-type tractor comprises a tractor body having thereon engine 2, and operator's seat 8 in back of the engine and adjacent the rear of the tractor. A bulldozer blade 4 is mounted at the front of the tractor, and is connected thereto by means including struts 8 secured to truck frames 1; one at each sideof the tractor. Each truck frame forms part of an endless track mechanism 8 which provides the ground engaging driving means for the vehicle.

The drive from engine 2 is transmitted to the endless track mechanisms 8 through the speed change transmission gearing of my invention, which is in a detachably mounted unitary transmission case 9; such speed change transmission gearing being connectable at will to the engine by master clutch mechanism ll of any suitable construction and which is adapted to be engaged or disengaged by clutch control lever l2 connected to the clutch through linkage i8. Control lever I2 is located at the operator's station in front of operator's seat 3 so as to be readily accessible to the operator.

' s Fig. 2 is a vertical longitudinal sectional viewof the transmission, taken in a plane indicated Case 8 includes front end wall 2|, rear end wall 22, top wall 23 having removable inspection cover 24 thereon, and bottom wall 26 having lubricant drain plug 21 screwed therein. Power from the engine is transmitted to the transmission when the master clutch is engaged and the engine is operating, by splined driving shaft 28 which is journalled in and extends through end walls 2| and 22 of the transmission case, and

which infront of front wall 2| is provided with a detachable coupling 28 to enable the entire transmission case and the gearing contained therein to be mounted and detached as a unit. In this connection, the rear end wall 22 of the transmission case is detachably connected to final drive and steering clutch case ii of the tractor by screws or studs 82. The rear end of driving shaft 28 which projects beyond rear end wall 22 of case 8, is splined to provide for the usual power take-01f for diving auxiliary equipment which may be associated with the tractor, and has secured thereto a pinion 88 connected to drive hydraulic steering clutch control mechanism (not shown). A suitable detachable bear ing and seal structure 84 provides a journal and sealing means between the front end of driving shaft 28 and front wall 2i; while a suitable bearing 88 provides a journal for the rear end of driving shaft 28 in rear wall 22.

Below driving shaft 28 and joumalied in walls 2i and 22 through suitable bearings 81, is a splined countershaft 88 which has a rear cluster gear "and a front cluster gear 4i secured for rotation v therewith but axially slidable therealong. Rear cluster gear 8.8 includes a small gear 42 adapted to mesh with a gear 48 fixed for rotation with a splined driven shaft 44 journalled adjacent its rear end in rear wall 22 'of the transmission case by means of bearing 48, and adjacent its front end in a partition wall 41 by bearing 48. A bevel pinion 88 at the rear-end of driven shaft 44 transmits the drive from such' driven shaft to final drive mechanism (not shown) connected to drive the endless track mechanisms.

Also, included in cluster gear 88 is a larger gear 48 adapted to mesh with a gear I also fixed to driven shaft 44. Front cluster gear 4i includes a small gear 82 and a larger gear 88 adapted to mesh respectively with gear 84 and gear 88 fixed to driven shaft 44. Axial displacement of gears 48, Ii, 84 and 88 on driven shaft 44 is precluded by virtue of the hubs of such gears being held in abutting relationship between rear wall 2! and partition wall 41. Cluster gear 88 is adapted to be shifted axially in either direction from a neutral position by shift mechanism, to be subsequently described in greater detail, which includes shifting fork 81; and cluster gear 4i is adapted to be similarly shifted by means including shift fork 88.

The described gearing comprises speed change gearing between countershaft I8 and driven shaft 44, which is relatively shiftable to provide a plurality of gear combinations for transmitting any selected one of a plurality of different speed drives through the-transmission when countershaft 88 is driven. Low speed obtains when gear 42 meshes with gear 48; second speed when gear 48 meshes with gear 8i; third speed when gear 82 meshes with gear 84; and fourth speed when gear 88 meshes with gear 88. A fifth speed may be obtained by a direct drive from the driving shaft 28 to the driven shaft 44, by means of a gear 8i rotatable with and axially slidable along driving shaft 88, and which is adapted to be moved from a neutral position to engage only gear 82 fixed to driven shaft 44. Shift mechanism including fork 88 is provided for shifting gear 8i along driving shaft 28. Although the gear combinations described provide for five different speeds through the transmission, it is apparent that any other, number of speeds may be obtained if so desired. by varying the number of gears between countershaft 88 and driven shaft 44, and between driving shaft 28 and driven shaft 44.

Means including reversible gearing interposed in the drive ahead of the speed change gearing associated with countershaft i8 and driven shaft 44, is provided for transmitting a drive from the driving shaft 28 through countershaft 38 to driven shaft 44' and such arrangement of the reversible gearing enables a forward or reverse drive for each of the plurality of combinations of gears between countershaft 88 and driven shaft 44. The reversible gearing comprises a pair ,of driving gears 84 and 88 within case 8 and which are formed as part of integral cluster gear 81 fixedly secured to driving shaft 28 behind front wall ii of case 8. Front gear 88, which is smaller than rear gear 84, meshes continuously with an idler gear 88 journalled on trunnion 88 fixed to cover 18 detachably secured to front wall If by cap screws Ii. Trunnion 88 is provided with lubricant passages 12 to supply lubricant to bearing I8 for gear 88; and a lubricant catch 14 is detachably secured to the rear end of trunnion 88 to receive lubricant for transmission to passages 11.

Below gears 84 and 88 is a gear I8 which is secured for rotation with and axially slidable in either direction along countershaft 38. When moved forwardly, gear 18 is adapted to mesh with idler gear 88; and when moved rearwardly, gear 18 is adapted to mesh with gear 84. Thus, depending upon which of gears 84 and 88, gear 18 meshes with, a forward or reverse drive may be selectively transmitted through countershaft 88 to driven shaft 44 for each of the combinations of gearing between countershaft 88 and driven shaft 44. The forward drive is when gear 18 meshes with idler gear 88; while the reverse drive is when gear 18 meshes directly with gear 84.

Control mechanism including a control lever to be subsequently described in greater detail and which is independent of a control lever for shifting the gearing between countershaft 88 and as driven shaft 44, is provided for shifting gear 18 through a shifting fork I1 connected to such gear.

Hence, when gear 8| is not meshed with gear 80 for each of the four speeds between countershaft 88 and driven shaft 44, without changing the relationship of any of the combinations of gearing between such shafts, merely by manipulation of shiftable gear 18. When the transmission is in high or fifth speed, namely, when gear 8| meshes with gear 82, a reverse drive cannot be transmitted. However when travelingin high speed. it is very seldom that the tractor need be reversed because such speed is generally intended for forward travel of thetractor without material load thereon. The character of gears 84 and I8 is preferably such as to provide a faster reverse speed for any selected speed drive through the relatively shiftable gearing between countershaft 88 and driven shaft 44, than the forward speed.

obtained by gears 88, 88 and 18. This makes for economy, because usually in backing up, the tracfor is not doing work but merely maneuvering to a position; and it is desirable to get to such position as quickly as possible.

By arranging the reversible gearing 84, 88, 88 and I8 in the transmission drive ahead of the relatively shiftable speed change gearing, an advantageousarrangement obtains enabling wide variations in the speed drive that may be transmitted through the various combinations of such relatively shiftable gearing, merely by providing various combinations of gears 80, 88, 08 and I8,

' and employing the desired combination upon in- Shift means of any suitable construction is provided; including a single gear shift lever ii, for shifting any one of gear 8|, cluster gear 80 comprising gears 42 and 49, or cluster gear comprising gears 52 and II; and a single auxiliary shift lever 82 is provided for shifting gear I0. The form of means descrbed herein comprises shifting fork 51 for cluster gear 30, which has an extension hub 81a fixedly secured to axially slidable shift shaft 51b; shifting fork II for cluster gear 4I, which has extension hub 580 secured to axially slidable shift shaft 58b; shifting fork 63 for gear M, which has an extension hub 03a,

secured to axially slidable shift shaft 88b; and shifting fork 11 for gear 10 which has an extension hub Ila secured to axially slidable shift shaft 11b. Shift shafts-5'lb, 0812,83?) and 11b are all mounted in an extension control housing 80 fixedly attached toa side of case 8; and shafts 51b, 58b and 83b have respectively fixedly secured thereto, as can be observed more clearly from Figs. 4 and 5, arms 51c, 58c and 080 which have respectively in their upper ends slots 81d, 58d and 63d. The central one'of these arms 580 is adapted to slide between spaced guides 85 fixed to extension control housing 84 and having opposite. slots 85'; and in the neutral position ofarms 51c, 58c and 83c, namely when none of the gears associated therewith is engaged, the slots 81d,

the guide 85 between such adjacent slots will'preclude movement of lever 01. to thereby obviate damage which might occur by simultaneous shifting of more than one shift arm. When end 88 of gear shift lever 8| engages in slot 8811 for shifting of gear 6f, the fifth or high speed position obtains, as was previously related. In such position, gear shift lever BI is adapted to be thrust forward or reverse drive, the hub 'I'Ia associated with shifting fork 11 and which is fixed to shift shaft 11b, has fixed thereto an arm 11c having a slot 'I'Id which opens upwardly and in which is always engaged the lower end 9| of a lever 02 fixedly secured to rockshaft 93 jo'urnalled in the upper part of extension housing 84. Shift lever 82 is fixedly secured to rock shaft 83 outside of housing 04;, and hence forward or backward movement of auxiliary shift lever 82 will effect movement of gear 18 for connecting it with either of driving gears 68 or 64.

Means is provided for preventing shifting of any of the gears when master clutch mechanism II is engaged, to thereby preclude damage to the transmission gearing which might otherwise occur should the operator inadvertently attempt to shift any of the gearingwhile the master clutch is engaged and a drive is transmitted to the transmission through driving shaft 28. As can be observed more clearly from Figs. 5, 7 and 9, each of shift shafts. 58b, 57b and 11b is provided with three wedge-shaped recesses or notches IOI, each of which is adapted to receive in latching engagement an associated spring loaded plunger I 02 having wedge-shaped end I03; while shift shaft 831) for shifting gear 6| has a pair of such wedge-shaped notches IOI each of which is adapted to receive in latching engagement a wedge-shaped end I03 of a similar associated plunger I02.

The central one of notches IN on each of shift shafts 58b, 51b and 11b, is adapted to receive the associated plunger I02 in the neutral position of the gearing associated with such shift shaft to latch such gearing in neutral; and the end notches on each of such shift shafts are adapted to receive the associated plunger I02 when the shift shaft is shifted in either one of opposite directions from the neutral position to mesh the gearing associated therewith, whereby such gearing is latched in all of their meshed positions. Because of the wedge-shaped character of notches MI and plunger ends I03, the shift shafts may be readily shifted into and out of notches engages the associated plunger I02 to latch gear GI in neutral position; and the other notch engages plunger 102 to latch gear 8i against a spring pressed plunger 01 slidably mounted in abracket 88 fixed to shift shaft 88b and integral with arm 880. A laterally projecting boss 80 may be provided on lever 8| adiacent end 86 thereof to engage plunger 81. The pur- I in any of slots lldJld and-08d.

For the shifting of gear II to provide for either when it meshes with gear 82. r

Locking means is also provided to lock the various plungers I02 when they are in proper engagement in notches IM and preclude shifting of the gearing when the master clutch is engaged. The ends I03 of plungers I02 opposite wedge-shaped ends I03 thereof project through a plate I00 clamped against extension housin 84' by means of a cap I08 which has journalled therein a locking shaft. I01 provided with an Such ends I03 are flat sided; and the recesses the shiftable gearing cannot be moved when the, master clutch is engaged because should attempt I be made to move any of shift shafts 03b, tub.

01b or' 11b axially, the wedge-shaped ends I of plungers I02 cannot be moved out of notches IOI inasmuch as ends I03 of plungers I02 would strike against the unrecessed portion of locking shaft I01. However, when the master clutch is disengaged, locking shaft I01 is moved through linkage I00 to the position where recess I08 therein is opposite the ends I00 of plungers I02. Hence, any of the shift shafts 00b, 00b, 51b and 11!), may be shifted in any desired direction only when the master clutch is disengaged; and when the gearing associated with any of such shift shafts is properly engaged and the master clutch is re-engaged, such gearing will be locked in proper position. For preventing axial displacement of locking shaft I01, it is provided with a peripheral groove III in which is engaged a plate IIO fixedly mounted in cap I00.

The control linkage I00 connecting locking shaft I01 to master clutch control lever I2 comprises arm II 0 fixedly secured to one end of a rock shaft II 1 journalled in bracket IIO mounted on the top of case 0: and at its opposite end, rock shaft H1 is connected to the lower end of lever I2. At its lower end, arm H0 is pivotally connected to a rod II9 which extends rearwardly through a collar 'I2I loosely mounted thereon but which is adapted at one end thereof to abut an abutment I22, fixed to such rod H0 and which may be conveniently secured by welding it to rod IIO. Collar I2I is spring thrust against abutment I22 by spring I about the projecting end of rod II! and which is interposed between a pair of spring retainers I20, one of which abuts collar I2I and the other one of which abuts spring pressure adjusting nut I20 fixed to the end of rod H0. Collar I2I has a laterally projecting pin I21 which is pivotally connected to lever I20 fixedlyattached to an end of looking shaft I01 which projects laterally beyond cap I00.

To disengage master clutch mechanism II, lever I2 must be moved to the right as it appears in Fig. 5. Such movement results in movement of rod IIO to the left with the result that abutment I22 will cause movement of collar III to the left with consequent movement of locking shaft I01 to the position where recess I00 is opposite ends I02 of locking plungers I02; and the gearing which is intended to be shifted by manipulation of either one or both of levers 0i and 02 may be so shifted. If the gearing shifted is properly meshed, the master clutch can 'be re-engaged by movement of lever I2 to the left, as it ap e s in Fig. 5. This results in locking shaft I01 being moved to locking position through a follow up action of spring I22 In effecting such shifting of the desired gearing, it is apparent that the proper shifted position thereof can only obtain when wedge-shaped end I00 of an associated plunger I02 is properly engaged in a notch IOI. Should such engagement not occur, and should the operator move control lever I2 to re-engage the master clutch after it has been disengaged for the shifting of gearing, movement of locking shaft I01 will be precluded because then end I03 of such plunger I02 will strike a straight side I30 which bounds recess I00 in locking shaft I01. If the operator were to force lever I2 to engage the master clutch under such circumstances, damage to the transmission might very readily occur. However, during such re-engagement of the clutch, rod IIO must be moved against the action of spring I23; and should any of plungers I02 be improperly positioned, spring I23 will be compressed to enable the operator to tell by the feel of lever I2 that the transmission is improperly meshed. Thus, spring I23 provides a yieldable connection in the control linkage I00, which indicates to the operator when the locking shaft I01 is in improper engagement with looking plungers I02 during establishment of a drive through the transmission, and which hence precludes damage to the transmission.

I claim: V

1. In a transmission, a driving shaft, a driven shaft; a countershaft, relatively shiftable speed change gearing associated with said driven shaft and said countershaft to provide a' plurality of gear combinations for transmitting any selected one of a plurality of different speed drives through said transmission, relatively shiftable speed change gearing associated with said driving shaft and said driven shaft for transmitting a drive directly from said driving shaft to said driven shaft, and reversible gearing between said driving shaft and said cc .intershaft for selectively establishing either a forward or reverse drive for each of said gear combinations associated with said driven shaft and said countershaft.

.2. In a transmission, a case, a driving shaft iournalled in said case, a driven shaft journalled in said case, a countershaft iournalled in said case, gearing within said case fixed to said driven shaft, gearing withinsaid case rotatable with but axially shiftable along said countershaft and cooperable with certain of said driven shaft gearing to provide a plurality of gear combinations for transmitting any selected one of a plurality of different speed drives through said transmission, other gearing within said case rotatable with but axially shiftable along said driving shaft and cooperable with other of said driven shaft gearing to transmit a drive directly from said drivin shaft to said driven shaft, and reversible gearing within said case between said driving shaft and said countershaft for selectively establishing either a forward or reverse drive for each of said gear combinations between said driven shaft and said countershaft.

HARMON S. EBERHARD. 

